Set of genes for use in a method of predicting the likelihood of a breast cancer patient&#39;s survival

ABSTRACT

The present invention relates to a set of genes for use in a method of predicting the likelihood of a breast cancer patient&#39;s survival or of predicting the likelihood of a recurrence and/or aggressiveness of a breast cancer in a breast cancer patient. The present invention also relates to a method for predicting the likelihood of a breast cancer patient&#39;s survival or the likelihood of the recurrence or aggressiveness of a breast cancer in a breast cancer patient, as well as to a kit for use in such method.

CROSS-REFERENCE TO A RELATED APPLICATION

This application is a continuation application of U.S. patent application Ser. No. 15/424,797, filed Feb. 4, 2017; which claims the benefit of U.S. Provisional Application Ser. No. 62/292,482, filed Feb. 8, 2016. This application also claims priority to European Patent Application No. EP 16154643.7, filed Feb. 8, 2016; all of which are incorporated herein by reference in their entirety.

The Sequence Listing for this application is labeled “SeqList-08Apr23.xml”, which was created on Apr. 8, 2023, and is 107.059 bytes. The entire content is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a set of genes for use in a method of predicting the likelihood of a breast cancer patient's survival or of predicting the likelihood of a recurrence and/or aggressiveness of a breast cancer in a breast cancer patient. The present invention also relates to a method for predicting the likelihood of a breast cancer patient's survival or the likelihood of the recurrence or aggressiveness of a breast cancer in a breast cancer patient, as well as to a kit for use in such method.

BACKGROUND OF THE INVENTION

Uncontrolled cellular growth and the ability to invade surrounding tissues are two basic characteristics of cancer. A complex multitude of changes in gene expression patterns exist in all cancers, and a growing body of evidence has linked aberrantly elevated and prolonged expressions of various genes and their mRNAs, respectively, to cancer, including genes participating in angiogenesis, chemotaxis and invasion. Examples of such genes include epidermal growth factor (EGF), estrogen receptor, cyclooxygenase-2, vascular endothelial growths factor (VEGF), matrix metalloproteinase, such as MMP-1 and MMP-9m, urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), chemokine receptor CXCR4 and several others.

Breast cancer is the most common invasive tumor disease in women on a global scale. According to estimates by the World Health Organization (WHO), there are more than 1 million new incidents of breast cancer worldwide per year. Various factors are believed to contribute to the occurrence of breast cancer, such as a genetic predisposition, hormonal factors, lifestyle habits, such as smoking, alcohol consumption, and lack of exercise. However, the exact etiology of breast cancer is not completely understood. Likewise it is also not possible to accurately predict the further course of the disease, once a patient has been diagnosed with breast cancer, nor is it possible to accurately predict what treatment should best be used for the individual patient.

BRIEF SUMMARY

The present invention provides for these and other similar needs. Accordingly, it was an object for the present invention to provide for markers that allow to predict the likelihood of a breast cancer patient's survival or the likelihood of a recurrence and/or metastasis of a breast cancer in a breast cancer patient. It was furthermore an object of the present invention to provide for a method for predicting the likelihood of a breast cancer patient's survival or the likelihood of the recurrence or metastasis of a breast cancer in a breast cancer patient.

BRIEF DESCRIPTION OF THE FIGURES

In the following, reference is made to the figures wherein

FIG. 1 shows the probability of survival of patients with an underexpression of ZFP36 and an underexpression of the 6 kb ELAVL1 variant. Because these species have a lower level of expression in cancer cells as opposed to normal cells, the plot uses inverted levels (1/x).

FIG. 2 shows the results of measurements of mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE, as probability of survival over time.

FIGS. 3 and 4 show a risk stratification of the same measurements when looking at the distant metastasis free survival (DMFS) in 2 (FIG. 3 ) and 3 groups (FIG. 4 ) as probability over time.

FIG. 5 shows risk stratification of the same measurements when looking at the distant metastasis free survival (DMFS) in 3 groups taking into account also the lymph node status, ESR1 expression and ERBB2 expression as probability of DMFS over time.

FIG. 6 shows the results of measurements of mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE, in combination with the mRNA expression levels ZFP36/ELAVL1 (using the ELAVL1 6 kb variant) taking into account also the lymph node status, ESR1 expression and ERBB2 expression, as probability of survival over time.

BRIEF SUMMARY OF THE SEQUENCES

SEQ ID NO: 1 is the sequence for the BIRC5 gene.

SEQ ID NO: 2 is the sequence for the CCNB2 gene.

SEQ ID NO: 3 is the sequence for the CDC6 gene.

SEQ ID NO: 4 is the sequence for the MMP13 gene.

SEQ ID NO: 5 is the sequence for the NEK2 gene.

SEQ ID NO: 6 is the sequence for the RRM2 gene.

SEQ ID NO: 7 is the sequence for the TOP2A gene.

SEQ ID NO: 8 is the sequence for the CENPE gene.

SEQ ID NO: 9 is the sequence for the MK167 gene.

SEQ ID NO: 10 is the sequence for the ZFP36 gene.

SEQ ID NO: 11 is the sequence for the ELAVL1 (6 kb variant) gene.

SEQ ID NO: 12 is the sequence for the ELAVL1 (1.5 kb variant) gene.

SEQ ID NO: 13 is the sequence for the ELAVL1 (2.7 kb variant) gene.

SEQ ID NO: 14 is the sequence for the ERBB2 gene.

SEQ ID NO: 15 is the sequence for the ESR1 gene.

SEQ ID NO: 16 is the sequence for the PGR gene.

SEQ ID NO: 17 is the sequence for the GAPDH gene.

SEQ ID NO: 18 is the sequence for the GUS gene.

SEQ ID NO: 19 is the sequence for the RPLPO gene.

SEQ ID NO: 20 is the sequence for the TUB gene.

SEQ ID NO: 21 is the sequence for the ACTB gene.

SEQ ID NO: 22 is the sequence for the 18SRNA gene.

DETAILED DESCRIPTION

All these objects are solved by a method for predicting the likelihood of a breast cancer patient's 5-year survival or the likelihood of recurrence of a breast cancer over a 5-year period in a breast cancer patient or the likelihood of a breast cancer patient's distant metastasis free survival (DMFS) over a 5-year period, said method comprising the steps:

-   -   measuring, in a tumor sample of said breast cancer patient, the         mRNA expression levels of 5, 6, 7, 8 or all genes of a set of         genes, said set of genes comprising, preferably consisting of     -   BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and,         optionally, MKI67     -   comparing the measured mRNA expression levels from said tumor         sample of said breast cancer patient with mRNA expression levels         of the same genes in a non-tumor sample of a healthy individual         or with mRNA expression levels of the same genes in a healthy,         non-tumor sample of the same breast cancer patient, and either     -   determining, based on such comparison, whether there is an         overexpression of the respective genes in said tumor sample of         said breast cancer patient,     -   wherein an overexpression of the mRNAs of each gene in said         tumor sample of said patient in comparison to the mRNA         expression levels of the same genes of said healthy individual         or in said healthy, non-tumor sample of the same breast cancer         patient is indicative of a likelihood of 5-year survival of <70%         and/or of a likelihood of recurrence of said breast cancer over         5-year period of >30% or of a likelihood of DMFS over a 5-year         period of <70%,     -   or     -   determining, based on such comparison, whether there is a low         overexpression, an intermediate overexpression or a high         overexpression of the respective genes in said tumor sample of         said breast cancer patient,

wherein a low overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <95% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >5% or of a likelihood of DMFS over a 5-year period of <95%, and

wherein an intermediate overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <85% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >15% or of a likelihood of DMFS over a 5-year period of <85%, and

wherein a high overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <70% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >30% or of a likelihood of DMFS over a 5-year period of <70%.

In one embodiment, said method additionally comprises

-   -   measuring the mRNA expression levels of ZFP36 (TTP) and ELAVL1         (HuR) in said tumor sample of said patient, wherein, preferably,         measuring ELAVL1 mRNA levels is a measuring of (i) all ELAVL1         variants or of (ii) a 1.5 kb and a 2.7 kb ELAVL1 variant or         of (iii) a 6 kb ELAVL1 variant,

-   and wherein a) an underexpression of ZFP36 or of the 6 kb ELAVL1     variant, or b) an overexpression of the 1.5 kb and 2.7 kb ELAVL1     variants, in comparison to the respective expression in a non-tumour     sample of a healthy individual or in a healthy non-tumour sample of     the same patient, or c) a ratio of ZFP36 mRNA expression: ELAVL1 1.5     and 2.7 kb variant mRNA expression <1

-   is indicative of a likelihood of 5-year survival of <70% and/or of a     likelihood of recurrence over a 5-year period of >30% of said breast     cancer.

In one embodiment, said method additionally comprises

-   -   measuring the mRNA expression levels of ERBB2, ESR1 and PGR in         said tumor sample of said breast cancer patient to classify the         type of breast cancer of said breast cancer patient according to         its expression or non-expression of ERBB2, ESR1 and/or PGR.

In one embodiment, said method additionally comprises

-   -   measuring the mRNA expression levels of any suitable         housekeeping gene(s) wherein, preferably said housekeeping         gene(s) is (are) selected from GAPDH, GUS, RPLPO, TUB, ACTB         and/or 18SRNA     -   in said tumor sample of said breast cancer patient, wherein any         measured mRNA expression levels of these housekeeping gene(s)         serves for normalization purposes, and wherein the measured mRNA         expression levels of said 5, 6, 7, 8 or all genes of said set of         genes and optionally of any other gene, such as ZFP36, ELAVL1,         ERBB2, ESR1 and/or PGR, are normalized against the measured mRNA         expression level(s) of said housekeeping gene(s).

-   In one embodiment, said tumor sample of said breast cancer patient     is a sample obtained from a breast cancer tumor of said breast     cancer patient or is a body fluid sample of said breast cancer     patient, preferably a body fluid containing exosomes, more     preferably blood or urine

In one embodiment, said method additionally comprises

-   -   assigning a treatment by chemotherapy if said likelihood of         5-year survival has been determined as being <70% and/or if said         likelihood of recurrence over a 5-year period has been         determined as being >30%, and/or

assigning a treatment by hormones, if said likelihood of 5-year survival has been determined as being >70% and/or if said likelihood of recurrence over a 5-year period has been determined as being <30%.

-   In one embodiment, measurement of mRNA expression levels occurs by     any of hybridization, preferably on a microarray, next-generation     sequencing, in-situ hybridization, RT-PCR, preferably quantitative     RT-PCR, flow cytometry, immunohistochemistry and any combination of     the foregoing. -   In one embodiment, measuring mRNA expression levels of said genes of     said set of genes is done using a corresponding set of probes which     are complementary to said genes or to the respective mRNAs of said     genes, wherein, preferably, said probes or primers consist of 10-100     adjacent nucleotides, wherein more preferably said probes or primers     are cDNA, cRNA, PNA, or DNA oligonucleotides. -   In one embodiment, expression of the mRNAs of each gene in said     tumor sample is an overexpression, if said mRNA expression levels in     said tumor sample are at least 1.5-fold, preferably at least     two-fold the mRNA expression levels of the same genes in a non-tumor     sample of a healthy individual or in a healthy, non-tumor sample of     the same patient.

In one embodiment, the genes have sequences designated as the following SEQ ID NOs:

{21 SEQ ID NO: 1 BIRC5 SEQ ID NO: 2 CCNB2 SEQ ID NO: 3 CDC6 SEQ ID NO: 4 MMP13 SEQ ID NO: 5 NEK2 SEQ ID NO: 6 RRM2 SEQ ID NO: 7 TOP2A SEQ ID NO: 8 CENPE SEQ ID NO: 9 MKI67 SEQ ID NO: 10 ZFP36 SEQ ID NO: 11 ELAVL1 (6 kb variant) SEQ ID NO: 12 ELAVL1 (1.5 kb variant) SEQ ID NO: 13 ELAVL1 (2.7 kb variant) SEQ ID NO: 14 ERBB2 SEQ ID NO: 15 ESR1 SEQ ID NO: 16 PGR SEQ ID NO: 17 GAPDH SEQ ID NO: 18 GUS SEQ ID NO: 19 RPLPO SEQ ID NO: 20 TUB SEQ ID NO: 21 ACTB SEQ ID NO: 22 18SRNA

-   In one embodiment, measuring the mRNA expression levels of 5 genes     of said set of genes is a measuring of the expression levels of     BIRC5, CCNB2, NEK2, RRM2, and TOP2A, and wherein measuring the mRNA     expression levels of 6 genes of said set of genes is a measuring of     the expression levels of BIRC5, CCNB2, NEK2, RRM2, and TOP2A, and     CENPE,     -   wherein said measuring the mRNA expression levels of said 5 or 6         genes is optionally in combination with measuring the mRNA         expression levels of ZFP36 (TTP) and ELAVL1 (HuR) in said tumor         sample of said patient, wherein, preferably, measuring ELAVL1         mRNA levels is a measuring of (i) all ELAVL1 variants or of (ii)         said 1.5 kb and said 2.7 kb ELAVL1 variant or of (iii) said 6 kb         ELAVL1 variant.

In one embodiment, said patient is a breast cancer patient who is either (i) ESR1-positive or ERBB2-negative, (ii) ESR1-positive and ERBB2-negative, (iii) ESR1-positive and/or PGR-positive and/or ERBB2-positive (“Luminal B breast cancer”), or (iv) ESR1-positive and/or PGR-positive, ERBB2-negative (“Luminal A breast cancer”), wherein optionally said patient is any of (i)-(iv) and said patient's lymph nodes are not affected by said breast cancer (“lymph node-negative”).

In one embodiment, said patient is a patient whose lymph nodes are not affected by said breast cancer (“lymph node-negative” patient).

-   In a further aspect the present invention also relates to a kit for     use in a method of the present invention, said kit comprising,     preferably consisting of probes for determining the expression of     mRNAs of 5, 6, 7, 8 or all genes of a set of genes, and said kit     optionally also consisting of probes for determining expression of     mRNAs of each of ZFP36 and ELAVL1, and/or of ERBB2, ESR1 and PGR,     and/or of GAPDH, GUS, RPLPO, TUB, ACTB and 18SRNA, and of means for     detecting a hybridization event between any of said probes and a     corresponding mRNA in a sample of a patient,

said set of genes consisting of

-   -   BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and         optionally MKI67, said probes being for determining the         expression of mRNAs of each gene of said set in a sample of a         patient having breast cancer or being diagnosed with breast         cancer.

-   In one embodiment, the kit according to the present invention     additionally comprises, preferably additionally also consists of     probes for determining expression of mRNAs of each of ZFP36 and     ELAVL1.

-   In one embodiment, the kit according to the present invention     additionally comprises, preferably additionally also consists of     probes for determining expression of mRNAs of ERBB2, ESR1 and PGR.

-   In one embodiment, the kit according to the present invention     additionally comprises, preferably additionally also consists of     probes for determining expression of mRNAs of at least one     housekeeping gene, preferably selected from GAPDH, GUS, RPLPO, TUB,     ACTB and 18SRNA.

-   In one embodiment, the kit according to the present invention     additionally comprises, preferably additionally also consists of     means for detecting a hybridization event between any of said probes     and an mRNA in a sample of a patient.

In one embodiment, said probes are complementary to the mRNA sequences of said genes and consist of 10-100 adjacent nucleotides which are complementary to said sequences, wherein said probes are preferably any suitable nucleic acid probe for hybridization and/or quantification including but not limited to DNA oligonucleotides, cDNA, cRNA, PNA, or others.

In a preferred embodiment, the measuring of mRNA expression levels is done by amplification using appropriate RT-PCR primers (or -probes, such terms being used interchangeably herein) and subsequent quantification.

In one embodiment, for calculation purposes, the mRNA levels are sometimes expressed as weighted means, using a weighting factor, preferably as outlined in Example 1.

The present inventors have surprisingly found that a specific combination of 5, 6, 7, 8 or all genes of a set of genes which consists of the following genes: BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENP, and, optionally, MKI67, is particularly useful for predicting the likelihood of a breast cancer patient's survival or the likelihood of a recurrence of a breast cancer in a breast cancer patient. Preferably, such survival is a 5-year survival. In one embodiment, the recurrence of a breast cancer is a 5-year recurrence, i. e. a reappearance of the breast cancer within an interval of 5 years. The present inventors have identified a set of nine genes which are particularly suitable as prognostic markers and which are particularly suitable for predicting the likelihood of survival or of recurrence of a breast cancer. The inventors have found that if one takes a combination of five genes or six genes or seven genes or eight genes or nine genes, i. e. all of the genes of such gene set and measures mRNA-levels thereof in a tumor sample of a breast cancer patient, it is possible to use such mRNA-level measurements for predicting the likelihood of survival of said breast cancer patient. In one embodiment, a combination of five genes of the set of genes consists of BIRC5, CCNB2, NEK2, RRM2, and TOP2A. In one embodiment, a combination of six genes of the set of genes consists of BIRC5, CCNB2, NEK2, RRM2, TOP2A, and CENPE. In one embodiment, the set of genes consists of the five genes BIRC5, CCNB2, NEK2, RRM2, and TOP2A. In another embodiment, the set of genes consists of the six genes BIRC5, CCNB2, NEK2, RRM2, TOP2A, and CENPE.

The term “measuring the mRNA expression levels of x genes”, with x being an integer number selected from 5, 6, 7, 8 or 9, is meant to refer to a measurement of the mRNA expression levels of these x genes and not of x−1 genes or x+1 genes. Hence in a measurement of the mRNA levels of 5 genes, the mRNA levels of precisely 5 genes are measured, in a measurement of the mRNA levels of 6 genes, the mRNA levels of precisely 6 genes are measured, in a measurement of the mRNA levels of 7 genes, the mRNA levels of precisely 7 genes are measured, in a measurement of the mRNA levels of 8 genes, the mRNA levels of precisely 8 genes are measured, and in a measurement of the mRNA levels of 9 genes, the mRNA levels of precisely 9 genes are measured (notwithstanding an optional measurement of any of the following group of expressions: (i) expression of genes pertaining to a classification of the breast cancer in terms of receptor expression and (ii) ZFP36/ELAVL1 expression and (iii) housekeeping gene expression. The term “housekeeping gene” is meant to refer to any gene that is constitutively expressed in a cell and required for maintaining basic cellular function; typically a housekeeping gene is expressed irrespective of whether a cell is in a normal healthy or a pathological state. Preferred examples of housekeeping genes as used herein are GAPDH, GUS, RPLPO, TUB, ACTB and 18SRNA.

In one embodiment, for measuring the mRNA-expression levels of each gene of said set of genes, one uses a corresponding set of probes or a corresponding set of primers which are complementary to said genes or to the mRNA of the respective genes. The terms “probes” and “primers” as used herein are used interchangeable. In one embodiment, said probes or said primers consist of 10-100 adjacent nucleotides. In one embodiment, said probes or said primers are complementary to said genes, in another embodiment, said probes or said primers are complementary to mRNAs of said genes. In one embodiment, said probes or said primers are complementary to the sense strand of the respective gene(s), in another embodiment, said probes or said primers are complementary to the antisense-strand of the respective gene(s). In a preferred embodiment, said probes or said primers are complementary to the mRNAs of the respective gene(s), and are cDNA.

The present inventors have surprisingly found that an overexpression of mRNA of the 5, 6, 7, 8 or 9 of the aforementioned genes, in a sample of a breast cancer patient, in comparison to the mRNA expression levels of the respective same gene(s) in a sample of a healthy individual or a healthy, non-tumor sample of the same (breast cancer) patient is indicative of a likelihood of a 5-year survival of <70%. Such an overexpression is or may also be indicative of a likelihood of a 5-year recurrence of breast cancer of >30%. Moreover, such an overexpression is or may also be indicative of a distant metastasis free survival over 5 years of <70%.

The term “metastasis-free survival” (MFS) or “distant metastasis-free survival” (DMFS) refers to the period after a curative treatment, when no disease can be detected, until a metastasis is detected. In the case of “distant metastasis-free survival”, such metastasis is detected in a tissue which is not breast tissue.

The term “healthy individual” as used herein is meant to refer to an individual not affected by breast cancer. The term “healthy sample” or “non-tumor sample” is meant to refer to a sample (e.g. of tissue) which is not affected by breast cancer. The term “tumor sample” is meant to refer to a sample (e.g. tissue) which is affected by breast cancer.

The term “overexpression”, as used herein, refers to an overexpression of gene(s) in the tumor sample of said patient in comparison to the expression of the same gene(s) in a non-tumor sample of the same patient or a non-tumor sample of a healthy individual. A measured mRNA expression level of said gene(s) in said tumor sample represents an “overexpression” over the measured mRNA expression levels of said gene(s) in a non-tumor sample of a healthy individual or in a healthy, non-tumor sample of the same breast cancer patient if the measured mRNA expression level(s) of said gene(s) in said tumor sample is at least 1.2-fold, preferably at least 1.5-fold, more preferably at least 2-fold the mRNA expression level(s) of the respective gene(s) in a non-tumor sample of a healthy individual or in a non-tumor sample of the same patient. An “overexpression” of the mRNA of a gene in a tumor sample, as used herein, is meant to refer to an increase of expression to an expression level which is at least 1.2-fold, preferably at least 1.5-fold, preferably at least 2-fold the expression level of the same mRNA in a healthy sample (“normal” expression level or “reference” expression level). An increase of expression to a level of 1-fold to 1.2-fold the normal level is herein also sometimes referred to as “low overexpression” or “low expression”. An increase of expression to a level of 1.2- to 2-fold, preferably 1.5- to 2-fold, the normal level is herein also sometimes referred to as “intermediate overexpression” or “intermediate expression”, and an increase to a level of more than 2-fold the normal level is herein also referred to as “high overexpression”. Such “low overexpression”, “intermediate overexpression” and “high overexpression” may be of importance if a patient cohort is classified into more than two risk groups, e.g. three risk groups. Such a stratification into more than two groups may give a better risk prediction.

-   Accordingly, in one embodiment, the method for predicting the     likelihood of a breast cancer patient's 5-year survival or the     likelihood of recurrence of a breast cancer over a 5-year period in     a breast cancer patient or the likelihood of a breast cancer     patient's distant metastasis free survival (DMFS) over a 5-year     period comprises the following steps:—     -   measuring, in a tumor sample of said breast cancer patient, the         mRNA expression levels of 5, 6, 7, 8 or all genes of a set of         genes, said set of genes comprising, preferably consisting of     -   BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and,         optionally, MKI67     -   comparing the measured mRNA expression levels from said tumor         sample of said breast cancer patient with mRNA expression levels         of the same genes in a non-tumor sample of a healthy individual         or with mRNA expression levels of the same genes in a healthy,         non-tumor sample of the same breast cancer patient, and     -   determining, based on such comparison, whether there is a low         overexpression, an intermediate overexpression or a high         overexpression of the respective genes in said tumor sample of         said breast cancer patient,

wherein a low overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <95% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >5% or of a likelihood of DMFS over a 5-year period of <95%, and

wherein an intermediate overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <85% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >15% or of a likelihood of DMFS over a 5-year period of <85%, and

-   -   wherein a high overexpression of the mRNAs of each gene in said         tumor sample of said patient in comparison to the mRNA         expression levels of the same genes of said healthy individual         or in said healthy, non-tumor sample of the same breast cancer         patient is indicative of a likelihood of 5-year survival of <70%         and/or of a likelihood of recurrence of said breast cancer over         5-year period of >30% or of a likelihood of DMFS over a 5-year         period of <70%.

In such an embodiment, the method preferably additionally comprises

-   -   assigning a treatment by chemotherapy if said likelihood of         5-year survival has been determined as being <70% and/or if said         likelihood of recurrence over a 5-year period has been         determined as being >30%, and/or     -   assigning a treatment by hormones, if said likelihood of 5-year         survival has been determined as being <85% and/or if said         likelihood of recurrence over a 5-year period has been         determined as being <15%, and/or     -   assigning no treatment, if said likelihood of 5-year survival         has been determined as being <95% and/or if said likelihood of         recurrence over a 5-year period has been determined as being         <5%.

The term “underexpression”, as used herein, refers to a lower expression of gene(s) in the tumor sample of said patient in comparison to the expression of the same gene(s) in a non-tumor sample of the same patient or a non-tumor sample of a healthy individual. A measured mRNA expression level of said gene(s) in said tumor sample represents an “underexpression” over the measured mRNA expression levels of said gene(s) in a non-tumor sample of a healthy individual or in a healthy, non-tumor sample of the same breast cancer patient if the measured mRNA expression level(s) of said gene(s) in said tumor sample is less than the mRNA expression level(s) of the respective gene(s) in a non-tumor sample of a healthy individual or in a non-tumor sample of the same patient.

The term “recurrence”, as used herein is meant to refer to the reappearance of breast cancer within a defined period of time. For example a 5-year recurrence refers to a reappearance of breast cancer in a patient within 5 years after a curative treatment when no disease can be detected.

The term “5-year survival” refers to a period of survival for five years after a timepoint at which timepoint no disease could be detected (e.g. because of a curative treatment that had taken place or because of a spontaneous disappearance of the breast cancer). The term “relapse-free survival” (also abbreviated as “RFS”) refers to a survival period measured over time in which period no disease can be detected.

In one embodiment, the measurements of mRNA expression levels of the 5, 6, 7, 8 or all of the genes of said set of genes is combined with measurements of mRNA expression levels of ZFP36 (also referred to as “zinc finger protein 36 homolog” or “tristetraproline” or “TTP”) and measurement of mRNA expression levels of ELAVL1 (also referred to as “ELAV-like protein 1” or “human antigen R” or “HuR”). The inventors have surprisingly found that ZFP36 mRNA expression levels are generally 3- to 6-fold decreased in breast cancer tissue in comparison to normal, i.e. healthy, tissues, i.e., they are only ⅓^(rd) to ⅙^(th) of the expression in healthy tissues. Moreover, the inventors found that ELAV1mRNA is overexpressed in breast cancer tissue of a breast cancer patient, if one looks at a polyadenylation variant of 2.7 kb of ELAVL1. ELAVL1 has three variants namely a 1.5 kb variant, a 2.7 kb variant which is the most abundant form, and another, less abundant, 6 kb variant. The 1.5 and 2.7 kb variants mRNA is/are overexpressed in breast cancer patients with a poor prognosis, whereas the longer (6 kb) variant is under-expressed in breast cancer patients with a poor prognosis compared with normal/healthy tissues. A combination of the measurements of the mRNA expression levels of the above-mentioned 5, 6, 7, 8 or 9 genes from the above-mentioned set of genes, with a measurement of the mRNA expression levels of ZFP36 and ELAVL1 even improves the prognostic value of such measurements. Because, in breast cancer tissues, ZFP36 is under-expressed, as is the 6 kb variant of ELAVL1, for calculation purposes, in embodiments of the present invention, one typically works with the reciprocal values of these under expressed genes (or mRNAs). If, instead, one looks at the expression of the shorter 1.5 or 2.7 kb variants (which are overexpressed in breast cancer tissue in comparison with normal tissue), for calculation purposes, in embodiments of the present invention, one uses the measured mRNA levels as such. A combination of the aforementioned measurements of the mRNA levels, i. e. of the expression of the 5, 6, 7, 8 or 9 genes, together with measurements of the mRNAs of ZFP36 and ELAVL1, can increase the accuracy of the prognosis even further. In one embodiment, the method according to the present invention additionally comprises a measuring of the mRNA expression levels of ZFP36 (TTP) and the mRNA expression levels of ELAVL1 (HuR) in said tumor sample of said patient, wherein measuring ELAVL1mRNA levels is a measuring of the 1.5 kb, the 2.7 kb and/or the 6 kb variant of ELAVL1. Because, in breast cancer patients with a poor prognosis of 5-year survival, ZFP36 is typically under-expressed and ELAVL1 is overexpressed (as far as the expression of the 1.5 and 2.7 kb variants are concerned), a ratio of such expression levels being <1 is indicative of a likelihood of 5-year survival <70%.

In one embodiment, the method additionally comprises measuring the mRNA expression levels of the ERBB2, ESR1 and PGR in said tumor sample of said breast cancer patient to classify the type of breast cancer of said breast cancer patient according to its expression or non-expression of ERBB2, ESR 1 and/or PGR. The term “ERBB2”, as used herein, is meant to refer to the human epidermal growth factor receptor 2, also referred to as “HER2/neu”. The term “ESR1”, as used herein, is meant to refer to estrogen receptor 1.

The term “PGR”, as used herein, is meant to refer to the progesterone receptor.

A person skilled in the art knows how to measure mRNA expression and is familiar with techniques for that purpose, such as hybridization, preferably on a microarray, next-generation sequencing, in-situ hybridization, RT-PCR, flow cytometry, immunohistochemistry etc. (see for example “Molecular Cell Biology”, Lodish et al. 2000, 4^(th) ed., eds. W.H.Freeman). A person skilled in the art is also familiar with techniques to detect hybridization events (ibid.; Alberts et al. “Molecular Biology of the Cell”, 2014, 6th ed., Garland Science), as well as with methods for the design and generation of suitable primers or probes. (ibid.)

Moreover, reference is made to the following examples which are given to illustrate, not to limit the present invention.

EXAMPLES Example 1: Methodologies

Cancer Patient Data

The Oncomine web-based data mining platform (www.oncomine.com) was used to mine data from The Cancer Genome Atlas (TCGA) and METABRIC databases (Curtis C, Shah S P, Chin S F, Turashvili G, Rueda O M, Dunning M J, et al. The genomic and transcriptomic architecture of 2,000 breast tumours reveals novel subgroups. Nature. 2012; 486:346-52.). Gene expression levels for 389 and 1556 invasive ductal breast cancer samples were downloaded for TCGA and METABRIC datasets, respectively, along with the 61 and 144 corresponding matched normal samples. Cancer upregulated genes were sought using a threshold of 1.7-fold increase in mRNA expression and Q<0.0001. Intersecting 2396 upregulated genes with 3658 genes from the ARE database (ARED) allowed the identification of the over-expressed AU-rich element-containing genes. Log 2 median-centered intensity ratios were used. Other cancer datasets were used and extracted through Oncomine and Nextbio portals.

Regression and Statistical Analysis

Linear regression and Pearson pairwise correlations between the expression values of upregulated ARE genes and TTP/HuR ratios were determined for the TCGA data using GraphPad Prism, version 6 for Windows (GraphPad Software, La Jolla, Calif.). Multiple regression models (JMP®, Version 10, SAS Institute Inc., Cary, N.C., 1989-2007) were used to fit TTP, HuR and TTP/HuR mRNA ratio expressions with an upregulated ARE-gene list (414) and ARE-gene cluster set (23 genes). Concordance correlation was used to assess the goodness of fit (Lin 1989, Biometrics). Goodness-of-fit tests for TTP, HuR, and TTP/HuR were performed by comparing actual values to those predicted by the fit model using the standard least square test.

Weighted means were calculated by multiplying the mean by its weight for each gene. This was achieved by computing the function

${\overset{\_}{x} = \left( \frac{\sum{w_{i*}{mean}(i)}}{\sum w_{i}} \right)},{{- {here}}\left( w_{i = \frac{1}{{({SE}_{i})}^{2}}} \right)}$

and mean _((i)) is the average of the gene expression and (SE_(i)) is the standard error for each gene.

All data are presented as mean±standard error of the mean (SEM). Unpaired Student's t-test was used to analyze statistical difference when comparing two datasets, whereas one-way ANOVA was used for determining statistical significance for three or more datasets. The results with p<0.05 were considered significant and indicated as asterisks. Statistical analyses were performed using GraphPad Prism and JMP®, Version 10 as well as SPSS.

Clustering and Functional Annotation

Clustering analysis of the resulting genes was performed based on normal mixture modeling to extract the ARE-mRNAs with the most significant negative correlation with the TTP/HuR ratio. The Akaike Information Criterion (AIC) value was used as an indicator of goodness of fit (smallest AIC). The over-expressed ARE-mRNAs were then analyzed using the AIC value and Johnson's transformation, which resulted in a best-fit normal mixture. Supervised hierarchical clustering and heat map visualization of gene expression data were performed using Gene-E (Broad Institute). Functional enrichment was performed using several web-based resources, including GEneSeT analysis, Database for Annotation, Visualization and Integrated Discovery (DAVID), and STRING protein-protein interaction resource.

Cell Culture

The normal-like mammary cell lines MCF10A and MCF12A, and the breast tumorigenic cell lines MCF-7 and MDA-MB-231, and the HEK293 cells were obtained from ATCC (Rockville, Md., USA). MCF10A and MCF12A were cultured in Dulbecco's Modified Eagle Medium: F12 (DMEM: F12, Life Technologies, Grand Island, N.Y., USA) fortified with HuMEC supplement (Gibco, Thermofisher, Grand Island, N.Y.), 10% FBS and antibiotics. MDA-MB-231, MCF-7, and HEK293 cells were grown in DMEM supplemented with 10% FBS and antibiotics. Tet-On Advanced HEK293 cells were obtained from ClonTech (Mountain View, Calif., USA) and were cultured in DMEM supplemented with 10% Tet-System Approved FBS (ClonTech), 100 ug/mL G418 (Sigma), and 5% penicillin-streptomycin (Invitrogen, Carlsbad, Calif., USA).

Quantitative Real-Time PCR

Total RNA was extracted (TRI reagent, Sigma) and reverse transcribed as described previously (Al-Souhibani N, Al-Ghamdi M, Al-Ahmadi W, Khabar K S A. Posttranscriptional control of the chemokine receptor CXCR4 expression in cancer cells. Carcinogenesis. 2014; 35:1983-92). Quantitative real-time PCR (qPCR) was performed in multiplex using FAM-labeled Taqman primer and probe sets (Applied Biosystems, Foster City, Calif., USA) for the following: human BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and, MKI67, and optionally normalized to VIC-labeled human GAPDH as the endogenous control. Samples were amplified in triplicate in a CFX96 cycler (Bio-Rad), and quantification of relative expression was performed using the ΔΔCt method.

Survival Analysis

The Kaplan-Meier survival analyses were performed using the Kaplan-Meier plotter portal, a manually curated and comprehensive dataset for survival analysis that covers 54,675 genes in 4,142 breast cancer patients (Gyorffy B, Lanczky A, Eklund A C, Denkert C, Budczies J, Li Q, et al. An online survival analysis tool to rapidly assess the effect of 22,277 genes on breast cancer prognosis using microarray data of 1,809 patients. Breast Cancer Res Treat. 2010; 123:725-31.). The database was built from the gene expression and survival data extracted from the European Genome-Phenome Archive (EGA) and the Gene Expression Omnibus (GEO) repositories. Overall survival (OS), recurrence-free survival (RFS), and distant metastasis free survival (DMFS) were determined using gene cluster stratification. In addition, survival analysis in the METABRIC and TCGA RNA sequence databases was performed separately. Associations between gene expression and patient survival were assessed by the Kaplan-Meier method (log-rank test, Graphpad 6.0). Kaplan-Meier analysis was performed as described previously (Mihaly Z, Kormos M, Lanczky A, Dank M, Budczies J, Szasz M A, et al. A meta-analysis of gene expression-based biomarkers predicting outcome after tamoxifen treatment in breast cancer. Breast Cancer Res Treat. 2013; 140:219-32.). The JETSET best probe set was selected in case multiple probe sets measured the same gene to ensure the optimal probe set for each gene. Hazard ratios and p-values were determined by Cox proportional hazards regression.

Example 2: Results

Associations between gene expression and patient survival were assessed by the Kaplan-Meier method (log-rank test). Survival data in association with gene expression data were collected from several public databases aided by web portals.

These resources include combined databases such as TCGA (tumor cancer genome atlas), METABRIC breast cancer data, and many others.

In all the examples, the proportion of patients surviving were plotted against time in months using two sets of groups reflecting two or more populations that are associated with two or more of relative gene expression, e.g., high and low, or high, intermediate and low. The median can be used as a cut-off between low and high in these plots. Any other cut-off statistical method that determine best percentile can be used. Values of gene expression are generally normalized to a housekeeping gene.

FIG. 1

Patient samples with gene expression data using the mean for inverted levels of ZFP36 and ELAVL1 6 kb were stratified into low and high expression based on the median. The proportions of patients surviving (Relapse-free survival, RFS) in each of this group were plotted against time. Hazard ratio (risk) with p-values are shown in the graph. Patients with high mean inverted levels of TTP and ELAVL1 6 kb mRNA had a poor survival outcome, while those with low inverted better survival outcome.

FIG. 2

Patient samples with gene expression data using the mean for the mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE were stratified into low and high expression based on the median. These mRNAs were chosen by the inventors because the inventors found that they bind to RNA-binding proteins, ZFP36 and ELAVL1 and are regulated by them and also over-expressed in cancer. The proportions of patients surviving (Relapse-free survival, RFS) in each of this group were plotted against time. Hazard ratio (risk) (HR) with p-values are shown in the graph. Patients with high median levels of expression had a poor survival outcome, while those with low median levels of expression had better survival outcome. More specifically, as can be seen from the figure, patients with an overexpression had a likelihood of 5-year survival of <70%.

FIG. 3

Patient samples with gene expression data using the mean for the mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE were stratified into low and high expression based on the median. The proportions of patients surviving (distant metastasis free survival (DMFS) in each of this group were plotted against time. Hazard ratio (risk) with p-values are shown in the graph. Patients with high median levels of expression had a poor survival outcome, while those with low had better survival outcome. More specifically, as can be seen from the figure, patients with an overexpression had a likelihood of DMFS over a 5-year period of <70%. It appears that the classification predicts better in case of patients who are lymph-node negative (i.e., their lymph nodes are unaffected by the breast cancer) and ER-positive.

FIG. 4

Patient samples with gene expression data using the mean for the mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE were stratified into three quantile groups low, intermediate, and high expression. The proportions of patients surviving (distant metastasis free survival (DMFS) in each of this group were plotted against time. Hazard ratio (risk) with p-values are shown in the graph. Patients with high median levels of expression had a poor survival outcome, while those with low median levels had better survival outcome. More specifically, as can be seen from the figure, patients with a high overexpression had a likelihood of DMFS over a 5-year period of <70%, patients with an intermediate overexpression had a likelihood of DMFS over a 5-year period of <85%, and patients with a low overexpression had a likelihood of DMFS over a 5-year period of <95%. It appears that the classification predicts better in case of patients who are lymph-node negative (i.e., their lymph nodes are unaffected by the breast cancer) and ESR1-positive.

The results of FIGS. 3 and 4 can be represented in the following Table 1:

TABLE 1 P value 3 groups p VALUE 2 groups ALL e−17 e−14 LYMPH NODE-NEGATIVE e−17 e−14 LYMPH NODE-POSITIVE 0.02 Ns ESR1-POSTIVE e−15 e−12 ESR1-NEGATIVE ns ns “ns” means “not significant”.

FIG. 5

Samples of patients who are both lymph-node negative and estrogen-receptor-positive (ESR1) were used. Gene expression data using the mean for the mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE were stratified into low and high expression based on the median. The proportions of patients surviving (distant metastasis free survival (DMFS) in each of this group were plotted against time. Hazard ratio (risk) with p-values are shown in the graph. Patients with the high median levels of the expression had a poor survival outcome, while those with low had better survival outcome. More specifically, as can be seen from the figure, patients with a high overexpression had a likelihood of DMFS over a 5-year period of <70%, patients with an intermediate overexpression had a likelihood of DMFS over a 5-year period of <85%, and patients with a low overexpression had a likelihood of DMFS over a 5-year period of <95%. It appears that the classification predicts better in case of patients who are lymph-node negative (i.e. their lymph nodes are unaffected by the breast cancer) and ER-positive.

FIG. 6

Patient samples with gene expression data using the mean for the mRNA expression levels of BIRC5, NEK2, CCNB2, RRM2, TOP2A, and CENPE, in combination with inverted levels of the mRNA expression of ZFP36 and ELAVL1 6 kb mRNA (long variant) were stratified into low and high expression based on the median. The proportions of patients surviving (RFS) in each of this group were plotted against time. Hazard ratio (risk) with p-values are shown in the graph. Patients with high median levels of expression had a poor survival outcome, while those with low had better survival outcome. More specifically, as can be seen from the figure, patients with an overexpression had a likelihood of 5-year survival of <70%, possibly even <60%. The correlation of such poor survival outcome is mostly stronger with ESR1-positive status. The results of FIG. 6 can also be represented in the following Table 2.

TABLE 2 HR p VALUE No. ALL 2.6  e−16 ERBB2-NEGATIVE 2.7  e−12 635 ERBB2-POSITIVE 0.83 NS 150 LYMPH NODE-NEGATIVE 2.22 e−6 1118 LYMPH NODE-POSITIVE 2.32 e−9 655 ESR1-POSTIVE 2.6 e−9 1802 ESR1-NEGATIVE 1.4 .02 313 “No.” refers to the number of patients; “HR” is hazard ratio. 

1. A method for predicting the likelihood of a breast cancer patient's 5-year survival or the likelihood of recurrence of a breast cancer over a 5-year period in a breast cancer patient or the likelihood of a breast cancer patient's distant metastasis free survival (DMFS) over a 5-year period, said method comprising the steps: measuring, in a tumor sample of said breast cancer patient, mRNA expression levels of at least 5 genes of a set of genes consisting of: BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and MKI67 comparing the measured mRNA expression levels from said tumor sample of said breast cancer patient with mRNA expression levels of the same genes in a non-tumor sample of a healthy individual or with mRNA expression levels of the same genes in a healthy, non-tumor sample of the same breast cancer patient, and either determining, based on such comparison, whether there is an overexpression of the respective genes in said tumor sample of said breast cancer patient, wherein an overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <70% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >30% or of a likelihood of DMFS over a 5-year period of <70%, or determining, based on such comparison, whether there is a low overexpression, an intermediate overexpression or a high overexpression of the respective genes in said tumor sample of said breast cancer patient, wherein a low overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <95% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >5% or of a likelihood of DMFS over a 5-year period of <95%, and wherein an intermediate overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <85% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >15% or of a likelihood of DMFS over a 5-year period of <85%, and wherein a high overexpression of the mRNAs of each gene in said tumor sample of said patient in comparison to the mRNA expression levels of the same genes of said healthy individual or in said healthy, non-tumor sample of the same breast cancer patient is indicative of a likelihood of 5-year survival of <70% and/or of a likelihood of recurrence of said breast cancer over 5-year period of >30% or of a likelihood of DMFS over a 5-year period of <70%.
 2. The method according to claim 1, wherein said method additionally comprises: measuring the mRNA expression levels of ZFP36 (TTP) and ELAVL1 (HuR) in said tumor sample of said patient, wherein measuring ELAVL1 mRNA levels is a measuring of (i) all ELAVL1 variants or of (ii) a 1.5 kb and a 2.7 kb ELAVL1 variant or of (iii) a 6 kb ELAVL1 variant, and wherein a) an underexpression of ZFP36 or of the 6 kb ELAVL1 variant, or b) an overexpression of the 1.5 kb and 2.7 kb ELAVL1 variants, in comparison to the respective expression in a non-tumour sample of a healthy individual or in a healthy non-tumour sample of the same patient, or c) a ratio of ZFP36 mRNA expression: ELAVL1 1.5 and 2.7 kb variant mRNA expression <1 is indicative of a likelihood of 5-year survival of <70% and/or of a likelihood of recurrence over a 5-year period of >30% of said breast cancer.
 3. The method according to claim 1, wherein said method additionally comprises measuring mRNA expression levels of ERBB2, ESR1 and PGR in said tumor sample of said breast cancer patient to classify the type of breast cancer of said breast cancer patient according to its expression or non-expression of ERBB2, ESR1 and/or PGR.
 4. The method according to claim 1, wherein said method additionally comprises measuring mRNA expression levels of one or more housekeeping genes selected from GAPDH, GUS, RPLPO, TUB, ACTB and 18SRNA in said tumor sample of said breast cancer patient, wherein any measured mRNA expression levels of these housekeeping gene(s) serves for normalization purposes, and wherein the measured mRNA expression levels of said at least 5 genes of said set of genes, and optionally of any other gene, such as ZFP36, ELAVL1, ERBB2, ESR1 and/or PGR, are normalized against the measured mRNA expression level(s) of said housekeeping gene(s).
 5. The method according to claim 1, wherein said tumor sample of said breast cancer patient is a sample obtained from a breast cancer tumor of said breast cancer patient or is a body fluid sample containing exosomes of said breast cancer patient.
 6. The method according to claim 1, wherein said method additionally comprises: assigning a treatment by chemotherapy if said likelihood of 5-year survival has been determined as being <70% and/or if said likelihood of recurrence over a 5-year period has been determined as being >30%, and/or assigning a treatment by hormones, if said likelihood of 5-year survival has been determined as being >70% and/or if said likelihood of recurrence over a 5-year period has been determined as being <30%.
 7. The method according to claim 1, wherein measurement of mRNA expression levels occurs by hybridization, next-generation sequencing, in-situ hybridization, RT-PCR flow cytometry, immunohistochemistry or any combination of the foregoing.
 8. The method according to claim 1, wherein measuring mRNA expression levels of said genes is done using a set of probes that is complementary to said genes or to the respective mRNAs of said genes.
 9. The method according to claim 1, wherein expression of the mRNAs is an overexpression if said mRNA expression levels in said tumor sample are at least 1.5-fold the mRNA expression levels of the same genes in a non-tumor sample of a healthy individual or in a healthy, non-tumor sample of the same patient.
 10. The method according to claim 1, wherein the genes have sequences designated as the following SEQ ID NOs: SEQ ID NO: 1 BIRC5 SEQ ID NO: 2 CCNB2 SEQ ID NO: 3 CDC6 SEQ ID NO: 4 MMP13 SEQ ID NO: 5 NEK2 SEQ ID NO: 6 RRM2 SEQ ID NO: 7 TOP2A SEQ ID NO: 8 CENPE SEQ ID NO: 9 MKI67 SEQ ID NO: 10 ZFP36 SEQ ID NO: 11 ELAVL1 (6 kb variant) SEQ ID NO: 12 ELAVL1 (1.5 kb variant) SEQ ID NO: 13 ELAVL1 (2.7 kb variant) SEQ ID NO: 14 ERBB2 SEQ ID NO: 15 ESR1 SEQ ID NO: 16 PGR SEQ ID NO: 17 GAPDH SEQ ID NO: 18 GUS SEQ ID NO: 19 RPLPO SEQ ID NO: 20 TUB SEQ ID NO: 21 ACTB and SEQ ID NO: 22 18SRNA.


11. The method according to claim 1, wherein measuring the mRNA expression levels of 5 genes of said set of genes is a measuring of the expression levels of BIRC5, CCNB2, NEK2, RRM2, and TOP2A, and wherein measuring the mRNA expression levels of 6 genes of said set of genes is a measuring of the expression levels of BIRC5, CCNB2, NEK2, RRM2, TOP2A, and CENPE, wherein said measuring the mRNA expression levels of said 5 or 6 genes is optionally in combination with measuring the mRNA expression levels of ZFP36 (TTP) and ELAVL1 (HuR) in said tumor sample of said patient.
 12. The method according to claim 1, wherein said patient is a breast cancer patient who is either (i) ESR1-positive or ERBB2-negative, (ii) ESR1-positive and ERBB2-negative, (iii) ESR1-positive and/or PGR-positive and/or ERBB2-positive (“Luminal B breast cancer”), or (iv) ESR1-positive and/or PGR-positive, ERBB2-negative (“Luminal A breast cancer”).
 13. The method according to claim 1, wherein said patient is a patient whose lymph nodes are not affected by said breast cancer (“lymph node-negative” patient).
 14. A kit for use in a method of claim 1, said kit comprising probes for determining the expression of mRNAs of at least 5 genes of a set of genes, and said set of genes consisting of BIRC5, CCNB2, CDC6, MMP13, NEK2, RRM2, TOP2A, CENPE, and MKI67, said probes being for determining the expression of mRNAs.
 15. The kit according to claim 14, additionally comprising probes for determining expression of mRNAs of each of ZFP36 and ELAVL1.
 16. The kit according to claim 14, additionally comprising probes for determining expression of mRNAs of ERBB2, ESR1 and PGR.
 17. The kit according to claim 14, additionally comprising probes for determining expression of mRNAs of at least one housekeeping gene selected from GAPDH, GUS, RPLPO, TUB, ACTB and 18SRNA.
 18. The kit according to claim 14, additionally comprising means for detecting a hybridization event between any of said probes and an mRNA in a sample of a patient.
 19. The kit according to claim 14, wherein said probes are complementary to mRNA sequences of said genes and consist of 10-100 adjacent nucleotides which are complementary to said sequences, wherein said probes are cDNA, cRNA, PNA, or DNA oligonucleotides. 